A Fundamental Investigation of Threshold Stress in Dispersion-Strengthened Materials

本项目旨在整合位错解离和正爬升的概念，建立弥散强化铝合金（Al-Sc-Mg-Zr-SiC）高温蠕变的定量模型。一个创新的蠕变试样几何将阐明阈值应力机制和微观组织的演变蠕变变形。了解颗粒尺寸和分布对阈值应力和蠕变动力学的影响可以通过显微组织设计来开发高温铝合金。目前迫切需要建立基于位错基本参数的定量模型。本研究的主要目标是：(1)研究简单合金体系（Al-Sc， Al-Zr等）的变形特征，以便系统地了解它们的力学行为；(2)进行原位透射电镜（TEM）应变实验，测定其在滑翔和爬升运动中的位错速度；(3)利用实验确定的参数建立定量模型。这项工作涉及大学-工业-政府实验室-国家用户设施的结合。这项研究对色散增强的基本机制有了新的认识，超出了目前的技术水平。研究结果旨在开发用于各种高温技术的抗蠕变材料

The project is aimed at developing a quantitative model for high temperature creep of dispersion strengthened aluminum alloys (Al-Sc-Mg-Zr-SiC) by integrating the dislocation dissociation and positive climb concepts. An innovative creep specimen geometry will elucidate the threshold stress mechanisms and the microstructural evolution during creep deformation. An understanding of the influence of particle size and distribution on threshold stress and creep kinetics can lead to development of high temperature aluminum alloys by microstructural design. The development of quantitative model based on fundamental dislocation parameters is in dire need. Major goals of the study are: (1) to investigate the deformation characteristics in simpler alloy systems (Al-Sc, Al-Zr, etc) for a systematic understanding of their mechanical behavior; (2) to perform in-situ transmission electron microscope (TEM) straining experiments for determining dislocation velocities during their glide and climb movements; and (3) to develop quantitative model using the experimentally determined parameters. The work involves a combination of university-industry-government laboratory-national user facility.%%%This research develops new understanding of the fundamental mechanisms of dispersion strengthening beyond the current state of the art. The results are aimed at the development of creep-resistant materials for high-temperature applications in various technologies.***